The present invention relates to a ferromagnetic thin film having saturation flux density, a magnetostriction constant close to zero and fine corrosion resistance, and comprising Fe as its main component. And the present invention also relates to a magnetic head using such a ferromagnetic thin film.
In recent years, high density magnetic recording has been developed significantly. Especially, the advent of the perpendicular magnetic recording system is significantly improving the recording density. Since a part of the single pole type magnetic head for perpendicular magnetic recording is formed by an extremely thin main pole, magnetic saturation tends to occur at the tip of the main pole. To prevent this, a magnetic thin film having an extremely high saturation flux density is desired. In a conventional head for VTR as well, the increase in recording density tends to reduce the gap length and increase the coercive force of the recording medium. In order to sufficiently record/reproduce a signal onto/from a recording medium by using such a magnetic head, a magnetic material having a high saturation flux density is desired.
Further, in a thin film magnetic head used in the computer memory or the like, the film thickness at the tip of the magnetic pole must be made thin in order to increase the recording density. In order to prevent the magnetic saturation at the tip of the magnetic pole, therefore, a magnetic thin film having a high saturation flux density is desired.
As the material for head core, the ferrite materials such as Mn-Zn ferrite and the alloy materials such as Ni-Fe alloys (permalloy) and Fe-Al-Si alloys (sendust) have heretofore been put into practical use. All of these materials are approximately 10 KG or less in saturation flux density, resulting in a drawback that they cannot be used for high density recording and reproducing.
In recent years, therefore, the crystalline alloys of Fe-Ti alloy, amorphous alloys comprising Co as the main component and elements such as Zr, Ti, Hf, Nb or Ta as the glass forming element, and the like have undergone research and development. These alloys are approximately 14 KG or less in saturation flux density.
In general, alloys of Fe-Si family are known as materials of high saturation flux density. An alloy containing approximately 6.5 wt% (12 at%) of Si has a magnetostriction constant close to zero and a high saturation flux density close to 18 KG and is considered to be promising as a high Bs head material (JP-A-59-78503). Since the alloy of Fe-Si has poor corrosion resistance, however, rust is unadvantageously incurred during the head production process or during the use of the head.